Glaucoma is a disease of the eye which is characterized by a progressive loss of visual field due to irreversible damage to the optic nerve to the point where if untreated can result in total blindness. This loss of visual field, in one form of primary open angle glaucoma, or POAG, is associated with a sustained increase in the intraocular pressure (IOP) of the diseased eye. Moreover, elevated intraocular pressure without visual field loss is thought to be indicative of the early stages of this form of POAG.
There are a number of therapies that target reducing the elevated IOP associated with this form of POAG. The most common feature the topical administration of a beta adrenergic antagonist or a muscarinic agonist. These treatments while effective in lowering IOP can also produce significant undesirable side effects.
Another less common treatment for this form of POAG is the systemic administration of carbonic anhydrase inhibitors. However, these drugs also can bring about unwanted side effects, such as nausea, dyspepsia, fatigue, and metabolic acidosis.
U.S. Pat. Nos. 4,797,413, 4,847,289 and 4,731,368 disclose topically dosed thiophene sulfonamides which lower IOP by inhibiting carbonic anhydrase.
Thiophene bis-sulfonamides, which are carbonic anhydrase inhibitors useful for treating conditions attributable to a restriction of blood flow to the brain, including atherosclerosis, occlusion of blood vessels in the brain, stroke and other cerebra vascular diseases, are disclosed in the British Patent No. 1,516,024. Similar compounds are also disclosed in Justus Liebigs Annalen der Chemie, 1933, 501, 174-188 and in Phosphorus Sulfur, 1981, 10(1), 111-119.
Other thiophene bis-sulfonamides, which are carbonic anhydrase inhibitors useful as diuretics, are disclosed in the German Patent No. 1,096,916 and Journal of Medicinal and Pharmaceutical Chemistry, 1959, 1(6), 565-576.
The compounds of the present invention are new sulfonamides which are carbonic anhydrase inhibitors (CAIs) useful for lowering IOP without producing significant systemic side effects when delivered topically to the eye.